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RegisterFunction CVpooled (package PowerTOST) [🇷 for BE/BA]
Hi all,
I will take it in good spirit that for some it can be difficult to accept diverging opinions without lashing out in a personal fashion. My ambition with my everyday dialogue is to keep the conversation on the healthy side of the fine line that separates humor from venomous hints.
Heteroscedasticity, or non-homogenous variance, is a concrete and widespread matter that is an everyday concern at most pharmaceutical companies and CROs involved in multicenter trials. There are some compelling reasons for taking it seriously including scientific, ethical and pecuniary ones. The companies go to great lengths to control it as much as possible, including using the same equipment, having it calibrated at the same centralised metrology departments, use of same SOPs, and not least having all centres adhere to the same protocol. And much more. It is through such effort that companies can justify using a stats model that assume variance homogeneity implicitly. The alternative would be pretty nasty and untenable.
There is no particular scientific reason to assume variance homogeneity for studies done at different times, at different locations, under different designs, with different SOPs, using different equipment and protocols etc. If I am not mistaken this is what we are doing when we pool CVs like described here.
Note also the distinction between pooling effects, pooling effect ratios (they tend to be homogenous between sites) and pooling variances. I believe GMcP and other pooling proponents do not really allude to the latter?
I will take it in good spirit that for some it can be difficult to accept diverging opinions without lashing out in a personal fashion. My ambition with my everyday dialogue is to keep the conversation on the healthy side of the fine line that separates humor from venomous hints.
Heteroscedasticity, or non-homogenous variance, is a concrete and widespread matter that is an everyday concern at most pharmaceutical companies and CROs involved in multicenter trials. There are some compelling reasons for taking it seriously including scientific, ethical and pecuniary ones. The companies go to great lengths to control it as much as possible, including using the same equipment, having it calibrated at the same centralised metrology departments, use of same SOPs, and not least having all centres adhere to the same protocol. And much more. It is through such effort that companies can justify using a stats model that assume variance homogeneity implicitly. The alternative would be pretty nasty and untenable.
There is no particular scientific reason to assume variance homogeneity for studies done at different times, at different locations, under different designs, with different SOPs, using different equipment and protocols etc. If I am not mistaken this is what we are doing when we pool CVs like described here.
Note also the distinction between pooling effects, pooling effect ratios (they tend to be homogenous between sites) and pooling variances. I believe GMcP and other pooling proponents do not really allude to the latter?
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Pass or fail!
ElMaestro
Pass or fail!
ElMaestro
Complete thread:
- Function CVpooled (package PowerTOST) Elena777 2018-01-21 08:53
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Function CVpooled (lengthy answer) Helmut 2018-01-21 17:21
- Function CVpooled (lengthy answer) Elena777 2018-01-27 10:11
- Function CVpooled (package PowerTOST) ElMaestro 2018-01-27 22:28
- Common sense Helmut 2018-01-28 00:27
- Common sense ElMaestro 2018-01-28 08:43
- Alzheimer’s Helmut 2018-01-28 11:38
- Common sense ElMaestro 2018-01-28 08:43
- To pool or not to pool d_labes 2018-01-28 13:52
- Common sense Helmut 2018-01-28 00:27
- Function CVpooled (package PowerTOST)ElMaestro 2018-01-29 00:07
- Pooling is fooling? Helmut 2018-01-29 17:53
- Pooling is fooling? nobody 2018-01-29 19:21
- Life is good ElMaestro 2018-01-30 18:23
- Life is good nobody 2018-01-30 18:31
- Life is good ElMaestro 2018-01-30 18:23
- Pooling is fooling? nobody 2018-01-29 19:21
- Pooling is fooling? Helmut 2018-01-29 17:53
- Function CVpooled (lengthy answer) Helmut 2018-01-21 17:21
Ing. Helmut Schütz